Hm, most of the implementations that I have locked at, seem to need a navmesh or nodes, that need to be placed by hand. I would appreciate a solution, that works without manually setting navmeshes, nodes or similar things.

I want to implement a navigation / pathfinding for around 500 NPCs, that works for a dynamically changing enviroment (many moving objects). Examples for similar implementations are Picmin, Age of Empires or Left4Dead.